Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Mar. 31, 2013	Sep. 30, 2014 Segment
Accounting Policies [Abstract]
Number of operating business segment		1
Convertible senior notes, interest percentage		2.625%
Convertible senior notes, maturity date		Apr. 01, 2017
Amount of net loss increased due to out-of-period adjustment	$ 3.6
Out-of-period adjustment		In the first quarter of 2013, the Company recorded an out-of-period correcting adjustment that increased operating expenses and net loss by $3.6 million for the three months ended March 31, 2013. Management concluded that the adjustment was not material to the full year 2013 results or any previously reported financial statements.